Distributed field equipment data access method

ABSTRACT

A method of accessing data from field equipments by the host through intelligent network gateways which link field equipments over control network and the host over local area network is disclosed. A configuration software in the host is used to install intelligent network gateways and field equipments as virtual equipment data servers. After finishing installation, the virtual equipment data servers access update  store data of the field equipments continuously. Now, the virtual equipment data servers always possess the last field equipment data and can link any application program with a standard communication protocol. The application can integrate easily and high speed access data of a various of field equipments in the factory with only one standard communication protocol through distributed virtual equipment data servers.

FIELD OF THE INVENTION

[0001] The present invention provides a method to access data from field equipments by the host through intelligent network gateways over local area network.

BACKGROUND OF THE INVENTION

[0002] A conventional supervisory system is shown in FIG. 1 in which a variety of Field equipments 2 are connected to the host 1 through low speed serial port (e.g., RS-232 or RS-485). Multiple device drivers are installed in the host 1 to drive field equipments 2. The host 1 and field equipments 2 are a client-server architecture and the host 1 is always polling and reading data from Field equipments 2. However, the prior art shown in FIG. 1 suffers from low speed rate and short communication distance serial port that limits data response time and work range of the application system, and multiple device drivers in the host 1 that limits the expansion of the application system. The other solution for conventional supervisory system is shown in FIG. 2, in which a variety of field equipments 5 are connected to the host 3 through network gateways 4 which are used as communication protocol adaptor between serial port (e.g., RS-232 or RS-485) and Ethernet port. The host 3 thinks network gateways 4 acting as virtual serial ports. Similarly, It suffers from the same problem as the prior art shown in FIG. 1 except work range of the application system due to Ethernet.

SUMMARY OF THE INVENTION

[0003] The present invention is to provide a distributed field equipment data access method. A variety of field equipments are connected to the host through intelligent gateways, and configuration software in the host is used to establish intelligent network gateways and field equipments as virtual equipment data servers. The virtual equipment data servers always keep the last field equipment data and can link any application program with a standard communication protocol like Modbus/TCP. The method comprises these procedures:(a) Execute configuration software for installation and debug in the host; (b) Input configuration parameters of the host

intelligent network gateway and field equipments in configuration software; (c) Generate text-script configuration file and download it to relative intelligent network gateway; (d) Intelligent network gateway interprets configuration file and access

update

store data of field equipments continuously; (e) Intelligent network gateway and its connected field equipments become a virtual equipment data server; (f) Check virtual equipment data server right or not with debug tool in configuration software. If right, the virtual equipment data server installation is finished, if not, check the parameters already input and modify them from procedure (b); and (g) Application program in the host access data from virtual equipment data servers with a standard communication protocol of LAN.

BRIEF DESCRIPTION OF THE DRAWINGS

[0004]FIG. 1 presents schematically the connection of field equipments and a host in conventional supervisory system;

[0005]FIG. 2 presents schematically the connection of field equipments and a host through network gateways in conventional supervisory system;

[0006]FIG. 3 presents schematically the connection of field equipments and a host through intelligent network gateways in supervisory system with configuration software and virtual equipment data server, a preferred embodiment according to the invention;

[0007]FIG. 4 is a flowchart illustrating the procedures of distributed field equipment data access method according to the invention;

[0008]FIG. 5 presents schematically the virtual equipment data server installation with configuration software and application program accesses data from the virtual equipment data server.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Referring to FIG. 3, Field equipments 12 with Programmable Logical Controllers (PLCs) are connected to the host 10 through intelligent network gateways 11, which link PLCs over control network (e.g., RS-232) and link the host 10 over LAN like Ethernet. Furthermore, the host 10 can be Pentium III personal computer or above with Windows 95 or above. Configuration software with graphic user interface is executed in the host 10. In installation phase, it can simulate the connection of the host 10

intelligent network gateways 11 and field equipments 12 on-site with icons and lines in the active window, and user can click each icon to input relative configuration parameters. After finishing configuration input, it would generate a text-script configuration file, which contains basic-like commands holding all the input parameters including equipment types

communication port parameters

IDs

data read or write

access start address

access length

data buffers

access retry times

time-out . . . etc., and download the file to the relative intelligent network gateway 11 over Ethernet. The intelligent network gateway 11 is embedded with firmware of network communication protocol transfer relative field equipment device drivers a standard communication protocol configuration file interpreter. After the gateway 11 receives the configuration file download from the host 10, it has intelligence to interpret and execute the configuration file automatically and start to access update store field equipment data continuously. And now, the intelligent network gateway 11 and field equipments 12 become a virtual equipment data server, and the virtual equipment data server can be checked right or not with debug tool of configuration software. If right, the installation of a virtual equipment data server is finished; if not, check the parameters already input and modify them.

[0010] An exemplary text-script configuration file is generated for the scenario in which field equipment 12 OMRON_C200 PLC connects to the intelligent network gateway 11 with COM1_RS232 serial port, and data in DMO-24 of OMRON_C200 PLC are read and stored in the buffer 1 of the network gateway 11 continuously:

[0011] contents comments

[0012] !--- ;File header

[0013] AUTO ;Set automatic mode

[0014] COM1,9600,7,E,2,100,1 ;Set COM1 parameters

[0015] !==== ;Command header

[0016] [HOST_LINK] ;Procedure name

[0017] (COM1_RS232_OMRON_C200) ;Block name, COM No., and PLC type

[0018] COMMAND=READ ;Read PLC DM

[0019] ID=0 ;PLC ID No. 0

[0020] LENGTH=25 ;Read DM length 25

[0021] PLC_START=0 ;DM read start address 0

[0022] LINKLIST_START=0001 ;Data stored in buffer 1 of network gateway

[0023] - ;Block end

[0024] [END] ;Procedure end

[0025] !!!! ; Command end

[0026] In this example, the intelligent network gateway 11 and OMRON_C200 PLC become a virtual equipment data server according to the configuration file mentioned above, and the data server always keeps the last DMO-24 data of OMRON_C200 PLC in the buffer 1 of the intelligent network gateway 11.

[0027] As stated above, the intelligent network gateway 11 is provided with a standard communication protocol like Modbus/TCP to link the application program such as SCADA software in-Tocuh or i-Fix. In these application program, executing Modbus/TCP communication protocol link program of I/O server and tagname dictionary to link and define the data of the intelligent network gateway 11 to the application program in the host 10. The application program now access data from the virtual equipment data server over high speed Ethernet with Modbus/TCP (refer to FIG. 5), not from field equipments 12 over low speed serial port with OMRON_C200 PLC device driver.

[0028] While the invention has been described by means of specific embodiments, numerous modifications and variations could be made thereto by those skilled in the art without departing from the scope and spirit of the invention set forth in the claims. 

What is claimed is:
 1. Distributed field equipment data access method by the host through intelligent network gateways which link field equipments over control network and the host over local area network is disclosed, the method comprises the contents of: (a) A configuration software with graphic user interface for virtual equipment data server installation and debug executed in the host; (b) Configuration software in installation phase is used to input the configuration parameters of the host intelligent network gateways and field equipments; (c) Configuration software generates a text-script configuration file which contains basic-like commands holding all the input parameters, and download the file to the relative intelligent network gateway; (d) The firmware of network communication protocol transfer relative field equipment device drivers standard communication protocol configuration file interpreter is embedded in the intelligent network gateway. After the intelligent network gateway receives the configuration file download from the host, it interprets and executes the configuration file automatically; (e) The intelligent network gateway starts to access update store field equipment data continuously according to the contents of the configuration file, And now, the intelligent network gateway and field equipments become a virtual equipment data server; (f) Debug tool in Configuration software is used to check a virtual equipment data server right or not. If right, the installation of a virtual equipment data server is finished; if not, check the parameters already input and modify them. (g) A standard communication protocol is provided with the intelligent network gateway to link the virtual equipment data server and the application program in the host.
 2. The method of claim 1, wherein configuration software with graphic user interface allows simulating the connection of the host intelligent network gateways and field equipments on-site with icons and lines in the active window, and user can click each icon to input relative configuration parameters.
 3. The method of claim 1, wherein configuration software generates a text-script configuration file after finishing configuration input, which contains basic-like commands holding all the input parameters including equipment types communication port parameters IDs data read or write access start address access length data buffers access retry times, and time-out . . . etc., and download the file to the relative intelligent network gateway.
 4. The method of claim 1, wherein the intelligent network gateway makes itself and field equipments for a virtual equipment data server according to the configuration file download from the host, and accesses updates stores field equipment data continuously. The host accesses field equipment data from high speed virtual equipment data server, not from low speed field equipments.
 5. The method of claim 1, wherein the intelligent network gateway is provided with a standard communication protocol, consequently, a virtual equipment data server can link application programs which possess a standard communication protocol. 